1. Field
The following description relates to a method for manufacturing a conductive transparent substrate and the conductive transparent substrate, and more particularly, to a method for manufacturing a conductive transparent substrate in a highly efficient production process.
2. Description of Related Art
Recently, as various home electronic appliances and communication devices become digitalized and highly-advanced at a rapid pace, with the rapid expansion in the field of display, techniques for forming a conductive transparent substrate having low resistance and high transmittance are gathering a lot of attention.
The material of such a conductive transparent substrate must be transparent and exhibit low resistance and also exhibit high flexibility so as to be mechanically stable, and have a coefficient of expansion that is similar to that of the substrate so that even when a device made of the conductive transparent substrate is overheated or placed under a high temperature it is not disconnected or cause great changes in the sheet resistance.
Materials that can be currently used for conductive transparent substrates include metallic oxide, CNT (Carbon Nanotubes), graphene, polymer conductor, metal nano wire and the like. Of these materials, the method of using ITO (Indium Tin Oxide) to form a thin film in a vacuum method is most widely used, but since ITO is a ceramic material, it has low resistance against bending or flexing of the substrate, and thus cracks may be easily formed and spread, thereby degrading the properties of the electrode. Furthermore, there is also the problem of difficulty of activation through substitution of a tin dopant, and drawbacks of being amorphous which leads to high sheet resistances. Not only that, the price of indium which is the main material of ITO continues to increase by the rapid expansion of the flat panel display, mobile device, and touch panel markets, and limited reserves of the ITO serves as a problem in cost competitiveness of the transparent conductive film. Therefore, it is very important to develop an alternative material that could solve the problems of ITO electrodes in order to gain a competitive edge in the competition of display technology that is expected to be fierce.
In the case of using polymer conductors, a transparent conductive film is typically produced using materials such as polyacetylene, polypyrole, polyphenol, polyaniline, PEDOT:PSS, and the like, but most of these polymer conductors have problems that they have low dissolubility, the process of forming a transparent conductive film is fastidious, and the energy bandgap shows color below 3 eV. Coating a polymer conductor as a thin film in order to increase the transmittance will increase the sheet resistance which becomes a problem when actually used in a transparent electrode. Furthermore, most of these polymer conductors have insufficient atmospheric stability, which means that they may be rapidly oxidized in the air, thereby reducing the electrical conductivity. Therefore, securing stability is an important factor.
Many studies are being conducted on conductive transparent films where CNT, graphene, and metal nano wire are used, but such conductive transparent films have problems yet to be solved to use as conductive transparent films having low resistance, and thus have not reached the commercialization level.
As a new method to resolve the aforementioned problems, studies are being conducted actively on methods for forming a conductive transparent film of a metal mesh format where a metal with excellent electrical conductivity and mechanical strength is used. A method of forming a fine intaglio groove by an imprinting method and then filling a metal; a method of directly etching a resin layer surface or resin layer with a substrate simultaneously by laser to form a fine groove and then filling a metal layer; a method of vacuum depositing or surface coating a metal and then using a photo etching process, and a method of using a directly printing method such as flexo, gravure, gravure offset, reverse offset, and inkjet printing are being studied.
However, these methods have numerous limitations in realizing a fine line width, productivity problem by many processes, and efficiency problem of the need to produce a subject transcriptome according to the structure of a transparent electrode area and the like.
Therefore, it is necessary to study a method for producing a conductive transparent substrate that could overcome the limitations of conventional techniques.